Cathode ray character display system



Feb. 9, 1960 J. T. MONANEY 2,924,742

CATHODE RAY CHARACTER DISPLAY SYSTEM Filed March so, 1959 n! 9 o 62 55 LL 2 lull- O U 2" g ll- 2: a; E

E E '5 1-. 3 a E g g INVENTOR. E JOSEPH T. MCNANEV.

. ATTORNEY INPUT I 2,924,742 CATHODE RAY CHARACTER DISPLAY SYSTEM Joseph T. McNaney, La Mesa, CaliL, assignor to General Dynamics Corporation, Rochester, N.Y., a corporation of Delaware Application March 30, 1959, Serial No. 802,905

7 Claims. (Cl. 315-9) in the form of visual displays on cathode ray tube screens.

The growing need for high-speed information storage and access in diverse technological pursuits has in recent .years encouraged the development and subsequent improvement of the shaped beam cathode-ray tube.

This type of cathode-ray tube is a vacuum tube containing a character matrix within the envelope in addition to the electron gun, deflection means, and screen. The matrix is a thin plate or disk in the path of the electron beam containing a plurality of beam forming apertures shaped in the form of alphabetical, numerical or symbolic indicia. The deflection system responds to coded input voltages by selecting specific predetermined character shaped beams and directing them to the cathoderay tube screen. The coded input information may consist of a succession of pulses, as employed by telegraph or teletype systems, or a group of simultaneous binary impulses or bits on parallel input lines, as employed by computer systems, or it may be in the form of analogue signals. Where it is necessary to translate coded input information into a form to which the character selection system within the tube is responsive, auxiliary circuitry can be added.

Oftentimes it is desirable to display character information in the form of visual displays on a plurality of display tubes or repeater indicators. Ordinary large screen cathode-ray tubes of the type used in television receivers may be employed as repeater display tubes provided they are furnished with conventional video signals corresponding to the selected indicia, in synchronism with their raster-scan deflection signals. In accordance with this invention selected shaped beams of electrons within the shaped beam tubes are used to convert incoming code signals directly into corresponding video signals for character generation and display in the display tubes.

' Among the purposes of the present invention are the following:

To'provide apparatus capable of converting shaped electron beams into video signals;

To provide apparatus capable of converting electrical pulse-coded information into video signals for causing character information to be displayed on cathode-ray tubes;

To provide information indicia of high quality on a cathode-ray tube screen in response to electrical pulsecoded information;

To provide a small, relatively simple apparatus for converting electrical pulse-coded information into video signals; and

To provide means for converting an electrical pulsewithout intermediate change of energy state.

United States Patent ,coded information signal into a video signal directly.

2,924,742 Patented Feb. 9,. 1960 These and other purposes of the invention will become apparent from a consideration of the following description read in conjunction with the accompanying drawings, in which:

Figure 1 is a schematic representation of one form of the cathode-ray character display system of this invention; and V Figure 2 is an internal cutaway view of the target area of the raster-scan shaped beam tube.

Figure 1 shows an exemplary embodiment of the invention comprising a shaped beam cathode-ray tube 10 made of glass, metal, or any other material suitable for an evacuated cathode-ray tube structure; The envelope 12 has a beam generating means 13 located at one end for generating and projecting character shaped electron beams toward a target, a target anode 28 located at the other end, and beam deflection means 26 positioned intermediate the two ends for causing the beam to scan the target anode. A pulse amplifier 36 amplifies the resultant video signal, which is then applied to the, grid control element 42 of a conventional cathode-ray display tube 40. The display tube 40 comprises an evacuated envelope 41 having an electron beam generating unit 43 located at one end, an electron responsive screen 44 located at the other end, and a deflection unit 45 positioned intermediate the two ends to cause the electron beam 53 to scan a raster in accordance ,with the scanning deflection signals furnished by deflection signal generator 46. Raster scan control voltages from deflection signal generator 46 are supplied to the deflection means 26 in the shaped beam tube 10 and the deflection unit 45 in the display tube 40 through lines 47 so as to reproduce the anode raster scanning of the former on the screen 44 of the latter. The instantaneous intensity of the beam impinging on the screen 44'of the display tube 40 is directly related to the cathode-ray current simultaneously impinging on the target anode 28 of the shaped beam character generator 10. Pulse amplifier 36 amplifies the signal from target anode 28 and this amplified signal provides a high intensity control signal to control element 42. Thus a low energy cathode-ray beam within the shaped beam tube 10 is converted to a highlevel video output on the relatively large screen of the display tube 40.

The following is a detailed description of the illustrated embodiment of the invention. The beam generating means 13 in the shaped beam cathode-ray tube 10 comprises all the elements necessary to generate shaped beams and project them toward the target 28. An electron gun 14 contains a heating element 15 for raising the temperature of the cathode 17 to the thermionic level. A control element 19 substantially coaxial with the cathode 17 has a central orifice or aperture which is capable of controlling the flow of electrons therethrough. Accelerating electrodes 23 serve to increase the velocity of the electron beam 25. The lensing action of the control element in conjunction with the accelerating electrodes 23 causes the electron beam 25 to cross over or converge at a point 27 in the vicinity of the control element 19, and thereafter to diverge as shown by the diverging beam 29. A beam converging electrostatic lens 16 in the path of the diverging beam 29 refracts the electron beam, causing it to focus or reconverge at a second crossover point 33. A character matrix 18 intermediate the cathode 17 and the second crossover point 33 contains a plurality of apertures shaped in the form of characters such as letters, numbers, symbols, or other indicia. The matrix 18 divides the impinging electron beam into a corresponding plurality of character shaped streams 31. A selection means which may be an electrostatic deflection system of the type which provides coplanar-like deflection as described fully in US. Patent 3 No. 2,811,668 is centered on the second crossover point 33, an arrangement which permits coplanar-like deflectron. An aperture plate 22 intermediate the selection plate system 20 and the target anode 28 contains a central aperture 35 through which a selected electron stream 51 may be directed toward the target anode 28. A second deflection means 26 shown intermediate the aperture plate 22 and the target anode 28 serves to scan the electron beam 51 across the target anode 28. Although the deflection means 26 is shown as an electrostatic deflection system for scanning conventionally in so-called XY directions, other known types of deflection systems may be employed. Furthermore, the invention is not limited to the type of raster scanning described, but may utilize any of various other well known types of beam scanning.

The target anode 28 shown more clearly in the cutaway view, Figure 2, is a small conductive member projecting through the envelope 10 in substantially the center of the target area 37. It has a beam contact area 39 which is small relative to the diameter of the electron beam which it intercepts. In Figure 2 electron beam 51 of tube 10 is shown, for explanatory pru'poses, to have a cross section corresponding to the letter L. Under the dicated by dotted L 75, and is then horizontally deflected to the position indicated by dotted L 76. During this deflection the vertical bar of shaped electron beam 51 moves across contact area 39, which therefore has a momentary increase of current therethrough. In accordance with raster scan principles, electron beam 51 is repositioned and vertically displaced a small distance. It is again deflected horizontally, its vertical bar again producing a momentary increase of current through anode 28. This process is repeated until the horizontal bar of shaped beam 51 is deflected across contact area 39, at which time the increased current has a longer duration. Since the shaped beam is deflected in such a manner that the various parts thereof sequentially traverse anode contact area 39, it may be said that the anode scans the image-or that the image is scanned across .the anode.

As shown, anode 28 is electrically connected to pulse amplifier 36, which amplifies the fluctuations of electron beam current caused by the selected character shaped beam 51 within the shaped beam tube 10 sweeping across the contact area 39 of the target anode 28. The amplified fluctuations constitute video signals which are conducted to the control element 42 within the electron generating unit 43 of a cathode-ray display tube 40. Since electron beam 53 of tube 40 is being deflected synchronously with shaped electron beam 51, these video signals cause beam 53 to be selectively intensified. Thus, during the first few scansions of beam 53, the aforementioned momentary increases of current cause target 44 to produce a series of spots of light that are positioned to produce a vertical line. The longer-duration increases of current produce one or more horizontal lines, all of these lines being properly positioned so that screen 44 of tube 40 reproduces an L. In this way, screen 44 produces a pattern of light that corresponds with the cross section of shaped electron beam 51. One or more of these display tubes convert the video and deflection signals into visual presentations on the display tube screens.

The display system embodied in Figure 1 operates as follows. The coded input 49 from an information code source, communication system, storage device, computer, or the like, is first translated by a decoder 30 from binary language, if the incoming information is in binary code, into analogue equivalents to which the character selection system 20 within the shaped beam tube 10 is responsive. The decoder 30 also generates pulses for 4 triggering the deflection systems and the display tube intensity-blanking circuitry, as hereinafter described.

With regard to the beam deflection function the decoder 30 feeds a triggering pulse to the deflection generators 46 through line 70 for each successive character. Raster scan deflection or sawtooth control voltages which appear at output lines 47 of deflection generator 46 feed the deflection systems 26 and 45 of both cathode-ray tubes 10 and 40 in parallel. The deflection means 26 within the shaped beam cathode-ray tube 10 causes the selected electron stream 51 to sweep horizontally across the contact area 39 of target anode 28 in successive vertical increments in response to the control voltages in lines 47. Likewise the deflection unit 45, receiving an identical set of sawto'oth voltages, similarly sweeps the electron beam 53 across the screen 44 of the cathode-ray display tube 40. Thus electron beams 51 and 53 scan synchronously.

With regard to the character selection function the analogue output from the decoder 30 is raised to the necessary amplitude level by selection amplifier 32 and thence fed to the selection'plate system 20 within the shaped beam tube 10. The selection plate system 20 in response to specific voltage commands redirects the plurality of character shaped electron streams 31 issuing from the matrix 18 so as to cause a selected electron stream 51 to pass through the selection aperture 35. The stream 51 continues through the deflection system 26 toward the target anode 28, where a relatively small portion of the cross section impinges on the contact area 39. Since the shaped beam tube in this application is not required to produce a photic output by electron bombardment of an electron-sensitive fluorescent surface, the velocity to which the shaped electron beam is accelerated may be minimized to enhance the definition of the character image of the shaped beam. The shaped beam tube may preferably be operated at a low energy level, using amplifier 36 inserted in the video output line, to increase the pulse amplitude to a level commensurate with the display tube requirements. The amplified video pulses are fed to the control element 42 of the electron generating unit or electron gun 43 of the cathode-ray display tube 40. Since the electron beam 53 within the display tube scans in synchronism with the chosen electron stream 51 within the shaped beam tube 10, intensity modulation of the display tube beam 53 in accordance with the video signal derived from the shaped beam tube 10 yields an image on the screen 44 of the display tube 40. The image is an exact replica of the cross section of the chosen shaped electron stream 51 within the shaped beam tube 10. Furthermore, the display tube image may possess high contrast and brightness as the result of bo'mbardment of the screen by an electron beam 53 of high energy level. The image may be enlarged to any desired degree within the shaped beam tube by well-known means such as the inclusion of an electrostatic lensing system intermediate the deflection system 26 and the target anode 28.

With regard to the blanking function, circuitry within the decoder 30 senses the duration of each code group by means of well-known techniques and triggers the blanking amplifier 34 appropriately. The amplified output pulse from the blanking amplifier 34 may be fed either to the control element 19 of the shaped beam tube through line 71 or preferably to the pulse amplifier 36 for the purpose of blanking the visual output of the display tube 40 during the horizontal and vertical retrace and during the interval between the selection of successive indicia.

Figure 1 shows one set of deflection plates 20 for the purpose of character selection and a separate set of deflection plates '26 for the purpose of scanning, but it is perfectly feasible to eliminate the latter set in favor of a single deflection system for both selection and scanning. The lines 65 connecting the output of deflection generator '46 to the character selection system 20 within the shaped beam tube*'10 may beused when'lscan deflection plates26, and-theconnections thereto, are eliminated. In this latter embodiment the aperture plate 22 is unnecessary; the function of character selection is performed by the target anode 28 in conjunction with the deflection system 26.

Although this invention is described with a certain degree of "particularity,it should be understood that the embodiments shown are given by way of example only and that various changes in the configuration and arrangement of the elements comprising the invention may be made without departing from its spirit and scope as hereinafter claimed.

I claim:

1. A cathode ray display system comprising in combination, at least one cathode ray display tube having an electron responsive screen and an electron generating unit capable of generating and projecting an electron beam, at second cathode ray tube having at one end a targetanode and at the other end beam generating means for generating and projecting at least one character shaped electron beam toward said target anode, control voltages, deflection means responsive to said control voltages for deflecting said character shaped beam in a manner that said anode is scanned by the image of said character shaped beam, said anode in response to said scanning being capable of providing pulses to said electron generating unit for controlling the generation of said electron beam in said display tube, said display tube having a deflection unit responsive to said control voltages for deflecting said electron beam over a portion of said screen in substantial synchronism with the scanning of said character shaped beam.

2. A cathode ray display system comprising in combination, at least one cathode ray display tube having an electron responsive screen and an electron generating unit capable of generating and projecting an electron beam, a second cathode ray tube having at one end a target anode and at the other end beam generating means for generating and projecting at least one character shaped electron beam toward said target anode, deflection means responsive to control voltages for deflecting said character shaped beam in a manner that said anode is scanned by the image of said character shaped beam, said anode in response to successive impingement by electrons of said shaped beam being capable of providing pulses to said electron generating unit for controlling the generation of said electron beam in said display tube, said display tube having a deflection unit responsive to said control voltages for deflecting said electron beam over a portion of said screen in substantial synchronism with the deflection of said character shaped beam.

3. A cathode ray display system capable of displaying character information on a plurality of cathode ray tube screens comprising in combination, a plurality of cathode ray display tubes, each having an electron generating unit capable of generating and projecting an electron beam and an electron responsive screen, a shaped beam cathode ray tube having at one end a target anode and at the other end beam generating means for selectively generating and projecting character shaped electron beams toward said target anode, raster scan control voltages, de-

flection means responsive to said raster scan control voltages for deflecting said character shaped beams in a manner that said anode is scanned by the entire image of at least one of said character shaped beams, said anode in response to said scanning being capable of providing voltage pulses to said electron generating unit for controlling the generation of said electron beam in said display tube, said display tube having a deflection unit responsive to said raster scan control voltages for raster scanning said electron beam over a portion of said screen in substantial synchronism with the raster scanning of said character shaped beam causing a character image to be displayed on said screens.

4. A cathode raydisplay system ca'pableof displaying character information on a plurality of cathode ray tube screens comprising in combination, at least one cathode ray display tube having an electron responsive screen and an electron generating unit capable of generating and projecting an electron beam, a shaped beam cathode ray tube having at one end a target anode and at the other end beam generating means for generating and projecting at least one character shaped electron beam toward said target anode, said anode having a contact area for intercepting a portion of said character shaped beam, control voltages, deflection means responsive to said control voltages for deflecting said character shaped beam in a manner that said anode is scanned by the image of said character shaped beam, said anode in response to successive impingement by electrons of said shaped beam being capable of providing voltage pulses to said electron generating unit for controlling the generation of said electron beam in said display tube, said display tube having a deflection unit responsive to said control voltages for deflecting said electron beam over a portion of said screen in synchronism with the deflection of said character shaped beam causing a character image to be displayed on said screen.

5. A cathode ray display system capable of displaying character information on a plurality of cathode ray tube screens comprising in combination, at least one cathode ray display tube having an electron responsive screen and an electron generating unit capable of generating and projecting an electron beam, a shaped beam cathode ray tube having at one end a target anode and at the other end beam generating means for generating and projecting at least one character shaped electron beam toward said target anode, said anode having a contact area for intercepting portions of said character shaped beam, said contact area being substantially smaller than the area of the image of said character shaped beam, raster scan control voltages, deflection means responsive to said raster scan control voltages for deflecting said character shaped beam in a manner that said anode is scanned by the image of said character shaped beam, said anode in response to successive impingement by electrons of said shaped beam being capable of providing voltage pulses to said electron generating unit for controlling the generation of said electron beam in said display tube, said display tube having a deflection unit responsive to said raster scan control voltages for raster scanning said electron beam over a portion of said screen in synchronism with the scanning of said character shaped beam by said anode causing a character image to be displayed on said screen.

6. A cathode ray display system comprising in combination, at least one cathode ray display tube having an electron responsive screen and an electron generating unit capable of generating and projecting an electron beam, a second cathode ray tube having at one end a target anode and at the other end beam generating means for generating and projecting at least one character shaped electron beam toward said target anode, said anode being substantially smaller than said character shaped beam, deflection means for deflecting said char acter shaped beam in a manner that said anode is scanned by the image of said character shaped beam, said anode in response to successive impingement by electrons of said shaped beam being capable of providing output energy corresponding to the character image of said character shaped beam, said electron generating unit in said display tube being controlled in the generating of said electron beam by said output energy, said display tube having a deflection unit responsive to said control voltages for deflecting said electron beam over a portion of said screen in substantial synchronism with the scanning of said character shaped beam causing a character image similar to the image of said character shaped beam to be displayed on said screen. 7

7. In a cathode ray display. system, a cathode ray tube having at one end a target anode and at the other end beam generating means for generating 'and'projecting at least one character shaped electron beam toward said target anode, said anode being substantially smaller than said character shaped beam, deflection means for deflecting said character shaped beam in a manner that said anode is scanned by the'image of said character shaped beam, said anode in response to successive impingement by electrons of said shaped beam being capable of pro vidi-ng output signals corresponding to the character image of said charactershaped beam.

References Cited in the file of this patent 

